Question

How to calculate the percentage change between two values in Rust

Answer 1

fn percentage_change(old_value: f64, new_value: f64) -> Result<f64, &'static str> {
    if old_value == 0.0 {
        return Err("old_value cannot be zero");
    }
    Ok(((new_value - old_value) / old_value) * 100.0)
}

fn main() {
    let old_value = 45.0;
    let new_value = 57.0;

    match percentage_change(old_value, new_value) {
        Ok(change) => println!("Percentage change: {:.2}%", change),
        Err(err) => eprintln!("Error: {}", err),
    }
}




/*
run:

Percentage change: 26.67%

*/

 

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